The operation started early Wednesday, he said, with KDF forces capturing the town of Hayo. Six Al-Shabaab militants were killed in that operation.

"(The troops) then moved straight onto Afmadow," said Chirchir.

Military analysts believe that Afmadow is a key step in Kenya's campaign against Al-Shabaab, the Islamic militant group they have been fighting since they entered Somalia in October of last year. The town would serve as a staging point for any move on Kismayo, Al-Shabaab's stronghold in southern Somalia.

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"Afmadow is an important administrative town that was supplying Al-Shabaab fighters with money. It was their nerve center," said Chirchir. "After the fall of Amfadow there is only Kismayo."

Last week, the African Union Mission in Somalia (AMISOM) said it, along with Somali troops, had launched an offensive against militants in the Afgoye corridor, a densely-populated enclave near the volatile Somali capital of Mogadishu.

The corridor, which has been controlled by the al Qaeda-backed Al-Shabaab, is populated with one of the largest populations of internally displaced people. The African Union said the militants have blocked many aid agencies from operating in the area.

The campaign was "going well," AMISOM spokesman, Lt. Col. Paddy Nkunda said last week. "Al-Shabaab tried to fight, but they know they are about to lose Afgoye and our soldiers broke through their early resistance."

Al-Shabaab announced in February that it was tightening its ties to al Qaeda. It has long been considered a terrorist movement by the United States.

Al-Shabaab has waged an insurgency against Somalia's feeble Transitional Federal Government since 2007, but has suffered recent setbacks in its heartland in southern Somalia.

AMISOM and government forces drove Al-Shabaab fighters from the center of Mogadishu last year, while Kenyan troops crossed into southern Somalia in October to hit back for a rash of kidnappings it blamed on the group. Despite their efforts, however, Al-Shabaab has continued to launch terror attacks in the capital.

In a second operation, 14 Al-Shabaab militants were killed and 10 others injured Tuesday when a Kenyan Defense Forces naval ship engaged with militants at an Al-Shabaab seaport watch station, the KDF said.

"The incident occurred when a KDF naval ship was conducting routine sea patrol in the vicinity of (the) port of Kismayu," according to a KDF statement. Two on-shore structures were destroyed, officials said.